Henry Family Blog

An electrocardiogram is a non-invasive diagnostic tool.  It can record the electrical changes that accompany each cardiac cycle (heartbeat).  The heart generates an electrical current from impulse conduction.  This can be detected at the surface of the body.   The ECG helps to determine if the conduction pathway is abnormal, if the heart is enlarged, and if certain regions are damaged.

As the atrial fibers depolarize, the P wave appears.  After the P wave begins, the atria contract (systole).  The action potential slows at the AV node giving the atria time to contract and time for the ventricles to fill.  Next, the action potential moves rapidly through the bundle branches, purkinje fibers, and the ventricular myocardium producing the QRS complex.  The ventricular contraction occurs and QRS complex and continues through ST segment.  Finally, repolarization of the ventricles produces the T wave. 

See Above:

P wave: atrial depolarization

P to Q interval: conduction time from atrial to ventricular excitation

QRS complex: ventricular depolarization

T wave: ventricular repolarization

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